In the manufacture of a large number of industrial products, a vinyl substrate such as vinyl film is adhered or laminated to a great variety of substrates. In hot laminating processes, the vinyl substrate and the other ply or plies are adhered through the use of a suitable adhesive at elevated temperatures. Polyurethane adhesives have been used in such hot laminating processes but difficulties have been encountered. Plasticizers in the vinyl compositions migrate at elevated temperatures, the silicone coatings typically found on the vinyl substrates interfere with adhesion and production variations between the vinyl and the adhesive also interfere with adhesion.
It has now been found that the addition of certain agents to heat activatable polyurethane adhesives overcome the past difficulties and excellent adhesion to vinyl films can be achieved.
Accordingly, it is the object of this invention to provide a new method of improving the adhesion of a heat activatable polyurethane adhesive to a vinyl substrate thereby achieving improved laminated articles and to such new laminated articles. This and other objects of the invention will become apparent to those skilled in this art from the following detailed description.